assuming big men - center
russell, chamberlain, walton from the era i never saw!
kareem, akeem, david, ewing, moses
shaq never had an antagonist by the time he learned how to play the best centers were on the way out.

i'm not saying he isn't the greatest, but there are arguments to be made.

take kareem for instance. he was a more efficient scorer who won more (and wilt had a lot of help too, so don't blame all of it on magic. jerry west and elgin baylor were the best 2 and 3 of their era) made more all-nba teams and took home more mvp awards, played longer, and scored more total points than anybody. he also has a better playoff scoring average on better shooting (esp free throw shooting) despite having torn down his own averages by played at 40 and 41 years of age. hell, you can ignore everything else and just look at kareem's effectiveness in the post season. the captain's average jumps two points in the post season. wilt's dips 8 points.

i know the rebounds are attrociously one-sided, but that has a lot to do with the number of shots that were taken in the 60s / 70s being very high. even small forwards and guards were pulling down outrageous rebounding numbers because there were tons of fgas and tons of misses. if you factor in game pace i think wilt's rebounding average dips to something like 15, which is still brutalizing and amazing, but it's slightly less otherworldly.

it's not a definitive proof for kareem (not sure i believe there's a convincing case for anyone), but it's an argument anyway. personally i think the most talented big i ever saw was hakeem, but he didn't always rise to the occassion, and he didn't always have the team, so i don't think he can be counted ahead of so many more accomplished players. shaq also was totally unguardable and amazingly destructive to defenses in his prime.